Movement and Position

Distance is a scalar quantity representing how much ground an object has covered during its motion.
Distance does not take into account the direction of the motion.
It’s measured in metres (m).

Displacement is a vector quantity representing the object’s overall change in position.
Displacement takes into account the direction of the motion.
It’s measured in metres (m) as well, but with an attached direction (north, south, east, west, etc.).

Speed is the rate at which an object covers distance.
A fast-moving object has a high speed and covers a large distance in a short amount of time.
Average speed can be calculated by dividing the total distance travelled by the total time taken.

Velocity is a vector quantity representing the rate at which an object changes its position.
It takes into account direction, unlike speed.
Average velocity can be calculated by dividing total displacement by the total time taken.

Acceleration is a vector quantity that represents the rate of change of velocity of an object within a certain period of time.
It is measured in metres per second squared (m/s²).
It occurs when an object speeds up, slows down, or changes direction.

Motions of objects can be represented using motion graphs, including distance-time graphs and velocity-time graphs.
A horizontal line on a distance-time graph suggests the object is stationary.
A sloping line on a distance-time graph indicates steady speed, and the steepness of the slope represents the speed.
A curving line on a distance-time graph indicates acceleration or deceleration.
The gradient on a velocity-time graph represents the acceleration. A horizontal line shows steady speed.

Becoming confident in these concepts and definitions will aid in understanding more complex principles involved in forces and motion.